Investment material



- UNITED STATES cRoss REFERENCE PATIENT OFFICE.

LAURENCE J. GILBERT, OI VICKSBUBG, MISSISSIPPI.

INVESTMENT murmur...

No Drawing.

To all whomit may concern:

Be it known that I, LAURENCE J. GILBERT, a citizen of the United States, and resident of Vicksbur in the county of Warren and State of Mississippi, have invented a certain new and useful Im rovement in Investment Materials, of whlch the following is a full, clear, concise, and exact description. My invention relates to an investment material suitable for use by dentists in making all sorts of cast and soldered dental restorations.

All ofv the ingredients of my improved investment are com aratively cheap, and the investment materia is made from these inedients by simple, mechanical mixture in t e proportions hereinafter set forth.

The investment material of my invention is capable of setting and drying quickly, will not expand, contract or break under heating, and, even under high temperatures, will not in any way mar or discolor porcelain or other white teeth with which the investment may be in contact.-

My investment material economizes time for the dentist, as it can be placed over a gas or other flame five to ten minutes after mixing, and dries out quickly.

My investment material 1s particularly useful in making soldered bridges, because the investment will not mar or discolor white teeth, as before stated, and by reason of the further fact that the investment is capable of visually indicatin to the operator when the investment and the brid e parts supported therein have been heate to the temperature at which gold solder should be flowed over the severe bridge parts to secure the same together.

Having thus made a preliminary statement of the purposes, objects, and advantages of my invention, I shall now describe the investment in detail. The ingredients of my improved investment are silica, Portland cement, and (dental) plaster of Paris, mechanically mixed together inthe following proportlons (by measure) to wit Silica 2 parts.

Portland cement 3parts.'

(Dental) plaster of Paris 1 part.

Each of the ingredients is preferably in finely divided or powdered form, rior to he measurement thereof. The comp eted ina ncanoa filed August a, 1921. Serial no. 4sa,e2o.

color. Immediate y prior to use the dark gray investment material is mixed with sufficient water to give the mixture substantially the consistency of bread dough.

It will be unnecessary to explain how the investment material is used in'making inlays, onlays, dummies, plates and other cast restorations, since all persons familar with pros.- thetio dentistry will understand how to use the investment material for such purposes. It will suffice to state that my investment is especially adapted. for use 1n dental castmg, because it sets and dries very quickly, because it will not expand, contract, or break under heating, and because after the completion of the casting operation the inawa from t e finished casting. h I

T e color changing characteristic of my investment is also advantageous in dental casting, because the change in color advises vestment may be easily and cleanly broken the operator that his investment is hard and dry, that his pattern has burned out, (if he uses a wax pattern) and that his investment mold has been heated to the temperature which should be obtained before he forces his gold (or other metal) into the cavity of the mold.

Bridges are or'dinaril made by soldering porcelam teeth (or go d dummies) to an abutment or abutments, the abutments being in the form of crowns or inlays. Prior to solderin the several parts of the bridge together, t e same are ositioned upon a plaster or other model of t 1e patients mouth.

The bridge parts are then invested, the back (lingual surfaces) thereof being left exposed. The invested case is then gradually eated to the meltin point of eighteen carat 1g'lold solder, and t en with the aid of a ydrogen or other suitable blow pipe the solder is flowed over the abutments and intermediate teeth to secure the same to ther. My improved investment is especial y use ful in constructing bridges by the method as chalk when it has been heated to the melting point of ei hteen carat gold solder. Thus, the operatorinows that when his investment has become white it him to flow his solder.

Having thusdescribed the investment material of my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. A dental investment material consisting of a major portion of Portland cement, and minor portions of silica and plaster of Paris. i

2. A dental investment material consisting of plaster of Paris, and relatively greater portions of silica and Portland cement. V

3. A dental investment material consistis I time for ing of silica, Portland cement and plaster of Paris, the Portland cement being present in greater quantity than either of the other ingredients and the silica being present in greater quantity than the plaster of Paris.

4. A dental investment material which comprises silica, Portland cement and plasterof l aris', in the following proportions; (by

measure) to-wit;

Silica 2 parts. Portlandcement 3 parts. Plaster of Paris 1 part. 

